This could be possible, because a bard would know how to read. A warrior or archer probably wouldn't. Because the fir'bolg were from another land, and probably didn't have the same written language as others, and warriors were "Concripted before the age of 16 to fill the ranks of the army"… Or something. So most warriors or archers probably wouldn't be able to read. Hey this IS medevil times. People were not as educated then.
The reason the charecter in Myth 2 can read is because in myth two things were just begining, and guys could get a better education.